I always pre-wash fabric cuts from the bolt. If it's a batik fabric, I prefer to use Synthrapol to help remove any excess dye. If its a fabric color, such as red or purple, which usually tends to bleed easily then I use Retayne in the wash. I have a front-loading washer after owning top-loading ones for many years. The agitation of the top-loaders are so hard on the fabrics and finished quilts-even on the gentlest cycle due to the twisting motion. For those to whom I give quilts, I suggest taking them to a laundromat that has front-loaders. It's well worth the few dollars to give the quilts the tender loving care they deserve. In the Retayne washes I also throw in a color catcher just as a double check. I wash as many times as needed until the color catcher comes out without dye on it.
As for pre-cuts, those are easily washed in special netted laundry bags which were intended for use when washing lingerie and other delicate items. The Retayne and Synthrapol washes apply here as well. It does take extra time to iron all of the pieces but the peace of mind regarding shrinking of the fabric and bleeding is worth it.